U.S. patent application number 10/210714 was filed with the patent office on 2003-11-06 for stent coating device.
Invention is credited to Shekalim, Avraham, Shmulewitz, Ascher.
Application Number | 20030207019 10/210714 |
Document ID | / |
Family ID | 31494281 |
Filed Date | 2003-11-06 |
United States Patent
Application |
20030207019 |
Kind Code |
A1 |
Shekalim, Avraham ; et
al. |
November 6, 2003 |
Stent coating device
Abstract
The present invention is a method and device, which is suitable
for use in an operating theater just prior to implantation, for
selectively applying a medical coating to an implantable medical
device, for example a stent. Disclosed is a device for use with a
stent deployed on a catheter balloon. The device is configured to
apply a medical coating of a desired thickness to the surface of a
stent only. This is done by use of a drop-on-demand inkjet printing
system in association with an optical scanning device. The device
is further configured so as to, if necessary, apply a plurality of
layered coats, each layered coat being of a different coating
material, and if appropriate, different thickness. The section of
the housing in which the stent is held during the coating procedure
is detachable from the housing base. The detachable housing section
may be easily cleaned and re-sterilized or simply disposed or
simply disposed of.
Inventors: |
Shekalim, Avraham; (Nesher,
IL) ; Shmulewitz, Ascher; (Tel Aviv, IL) |
Correspondence
Address: |
Finnegan, Henderson, Farabow,
Garrett & Dunner, L.L.P.
1300 I Street, N.W.
Washington
DC
20005-3315
US
|
Family ID: |
31494281 |
Appl. No.: |
10/210714 |
Filed: |
July 30, 2002 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10210714 |
Jul 30, 2002 |
|
|
|
10136295 |
May 2, 2002 |
|
|
|
Current U.S.
Class: |
427/2.24 ;
118/668; 427/8 |
Current CPC
Class: |
B05B 13/0442 20130101;
B05C 5/0216 20130101; B05B 12/12 20130101 |
Class at
Publication: |
427/2.24 ; 427/8;
118/668 |
International
Class: |
A61L 002/00 |
Claims
What is claimed is:
1. A method for coating comprising: (a) providing a prosthesis
having identifiable features; (b) pre-scanning said prosthesis
prior to coating to identify said features and to obtain coating
coordinates for said features; and (c) applying a coating material
at desired regions of the prosthesis as a function of said
coordinates.
2. A method according to claim 1, further comprising: (d)
determining paths between said coating coordinates for an
applicator to deposit said coating material.
3. A method according to claim 2, further comprising: (e)
determining a sequence for said coating coordinates.
4. A method according to claim 3, further comprising: (f)
determining vectors between the coating coordinates in said
sequence.
5. A method according to claim 1, further comprising: (d)
determining a predetermined path independent of said coating
coordinates.
6. A method according to claim 5, wherein said predetermined path
covers a surface area of said prosthesis, wherein said surface area
comprises said coating coordinates.
7. A method according to claim 6, wherein said predetermined path
is a function of the overall contour or geometric shape of said
prosthesis.
8. A method according to claim 1, further comprising: (d)
post-scanning said prosthesis after coating.
9. A method according to claim 8, wherein said post-scanning
comprises rotating said prosthesis and detecting of said coated
prosthesis.
10. A method according to claim 1, wherein said pre-scanning
comprises rotating said prosthesis and detecting of said
prosthesis.
11. A method according to claim 10, wherein said detecting
comprises detecting energy from said identifiable features of said
prosthesis.
12. A method according to claim 11, wherein said pre-scanning
further comprises analyzing said images for edges associated with
said prosthesis.
13. A method according to claim 10, wherein said pre-scanning
further comprises determining said coating coordinates from said
edges.
14. A method according to claim 10, wherein said detecting
comprises capturing energy transmitted around identifiable features
of said prosthesis.
15. A method according to claims 14, wherein said pre-scanning
further comprises analyzing said images for the edges associated
with said prosthesis.
16. A method according to claim 15, wherein said pre-scanning
further comprises determining said coating coordinates from said
edges.
17. A method according to claim 1, wherein said coating material is
chosen from polymers, therapeutic agents, and mixtures thereof.
18. A method for coating comprising: (a) providing a prosthesis;
(b) pre-scanning said prosthesis prior to coating to obtain coating
coordinates for said prosthesis; (c) applying a coating material to
said prosthesis at said coating coordinates; and (d) post-scanning
said prosthesis after coating.
19. A method according to claim 18, wherein said applying comprises
translating an applicator and delivering drop-on-demand of a
quantity of coating from said coating applicator, wherein said
translating and said delivering are on-the-fly.
20. A method according to claim 18, wherein said applying comprises
raster type coating.
21. A method according to claim 18, wherein said applying comprises
vector type coating.
22. A method according to claim 18, wherein said pre-scanning
comprises rotating said prosthesis and detecting of said
prosthesis.
23. A method according to claim 18, wherein said pre-scanning
comprises rotating a detector and detecting of said prosthesis.
24. A method according to claim 18, wherein said post-scanning
comprises rotating said prosthesis and detecting of said coated
prosthesis.
25. A method according to claim 18, wherein said post-scanning
comprises rotating a detector and detecting of said coated
prosthesis.
26. A method according to claim 22, wherein said detecting
comprises capturing energy from said prosthesis or capturing energy
transmitted around said prosthesis.
27. A method according to claim 22, wherein said pre-scanning and
said post-scanning further comprises analyzing said images for
edges of said prosthesis.
28. A method according to claim 27, wherein said pre-scanning
further comprises determining said coating coordinates from said
edges.
29. A method according to claim 22, wherein said analyzing
comprises comparing images from said pre-scanning and said
post-scanning.
30. A method according to claim 29, wherein said analyzing further
comprises identifying coating errors.
31. A method according to claim 30, further comprising repeating
said coating to re-coat said prosthesis at coordinates associated
with detected coating errors.
32. A method according to claim 30, further comprising assigning a
coating quality approval to said coated prosthesis.
33. A method according to claim 22, wherein said analyzing
comprises optically distinguishing a first type of surface from a
second type of surface.
34. A method according to claim 33, wherein said analyzing further
comprises rendering a three-dimensional shape from said images.
35. A method according to claim 22, wherein said analyzing
comprises identifying pigment in a coating applied to said
prosthesis.
36. A method according to claim 18, wherein said coating comprises
jetting with hot air, wherein said hot air evaporates a volatile
solvent in a coating material.
37. A method according to claim 18, wherein said coating comprises
directing infrared radiation, wherein said infrared radiation
evaporates a volatile solvent in a coating material.
38. A method according to claim 18, wherein said coating material
is chosen from polymers, therapeutic agents, and mixtures
thereof.
39. A method for coating comprising: (a) providing a prosthesis
having identifiable features; (b) determining a predetermined path
independent of said features; and (c) applying a coating material
to the prosthesis at desired regions, wherein said regions are a
function of said features.
40. A method according to claim 39, wherein said predetermined path
covers a surface area of said prosthesis, wherein said surface area
comprises said desired regions.
41. A method according to claim 40, wherein said predetermined path
is a function of the overall contour or geometric shape of said
prosthesis.
42. A method according to claim 40, wherein said applying comprises
raster type coating.
43. A method according to claim 39, wherein said coating material
is chosen from polymers, therapeutic agents, and mixtures
thereof.
44. An apparatus for coating comprising: an applicator for applying
a coating material to a prosthesis; a detector for scanning said
prosthesis; and an applicator controller connected to said detector
and said applicator, wherein said applicator controller is adapted
to on-the-fly coating.
45. An apparatus according to claim 44, wherein said prosthesis
comprises identifiable features for which said detector provides
coating coordinates for said applicator controller.
46. An apparatus according to claim 45, wherein said applicator
controller is adapted to determine paths between said coating
coordinates for said applicator.
47. A system for coating comprising: (a) providing a prosthesis
having identifiable features; (b) means for pre-scanning said
prosthesis prior to coating to identify said features and to obtain
coating coordinates for said features; and (c) means for applying a
coating material at desired regions of the prosthesis as a function
of said coordinates.
48. A system according to claim 47, further comprising: (d) means
for determining paths between said coating coordinates for an
applicator.
49. A system according to claim 48, further comprising: (e) means
for determining a sequence for said coating coordinates.
50. A system according to claim 49, further comprising: (f) means
for determining vectors between the coating coordinates in said
sequence.
51. A system according to claim 47, further comprising: (d) means
for determining a predetermined path independent of said coating
coordinates.
52. A computer program product for coating, the computer program
product comprising computer-readable media having computer-readable
code, the computer program product comprising the following
computer-readable program code for effecting actions in a computing
platform: (a) program code for providing a prosthesis having
identifiable features; (b) program code for pre-scanning said
prosthesis prior to coating to identify said features and to obtain
coating coordinates for said features; and (c) program code for
depositing a coating material at desired regions of the prosthesis
as a function of said coordinates.
53. A computer program product according to claim 52, further
comprising: (d) program code for determining paths between said
coating coordinates for an applicator.
54. A computer program product according to claim 53, further
comprising: (e) program code for determining a sequence for said
coating coordinates.
55. A computer program product according to claim 54, further
comprising: (f) program code for determining vectors between the
coating coordinates in said sequence.
56. A computer program product according to claim 52, further
comprising: (d) program code for determining a predetermined path
independent of said coating coordinates.
57. An applicator control module comprising: an applicator adapted
to drop-on-demand a quantity of coating material at a desired
location of a prosthesis; and an applicator controller adapted to
on-the-fly coating.
58. An applicator control module according to claim 57, wherein
said applicator controller comprises of a servo controller, a
driver for said applicator, and a location feedback device.
Description
[0001] This is a continuation-in-part of U.S. patent application
Ser. No. 10/136,295, filed on May 2, 2002.
FIELD OF THE INVENTION
[0002] The present invention relates to coating medical devices
intended for in vivo deployment and, in particular, a method and
device suitable for use in an operating theater just prior to
implantation, for selectively applying a medical coating to an
implantable medical device, for example a stent.
DEFINITIONS
[0003] The term "prosthesis" refers to any one of many medical
coating applications including but not limited to coronary stents,
peripheral vascular stents; abdominal aortic aneurysm (AAA)
devices, biliary stents and catheters, TIPS catheters and stents,
vena cava filters, vascular filters and distal support devices and
emboli filter/entrapment aids, vascular grafts and stent grafts,
gastro enteral tubes/stents, gastra enteral and vascular
anastomotic devices, urinary catheters and stents, surgical and
wound drainings, radioactive needles and other indwelling metal
implants, bronchial tubes and stents, vascular coils, vascular
protection devices, tissue and mechanical prosthetic heart valves
and rings, arterial-venous shunts, AV access grafts, surgical
tampons, dental implants, CSF shunts, pacemaker electrodes and
leads, suture material, wound healing, tissue closure devices
including wires, staplers, surgical clips etc., IUDs and associated
pregnancy control devices, ocular implants, timponoplasty implants,
hearing aids including cochlear implants, implantable pumps (like
insulin pumps), implantable cameras and other diagnostic devices,
drug delivery capsules, left ventricular assist devices (LVADs) and
other implantable heart support and vascular systems, indwelling
vascular access catheters and associated devices (like ports),
maxilo fascial implants, orthopedic implants (joint replacement,
trauma management and spine surgery devices), implantable devices
for plastic and cosmetic surgery, implantable meshes (such as for
hernia or for uro-vaginal repair, brain disorders, and
gastrointestinal ailments).
[0004] The term "drop-on-demand" refers to any active or passive
release of a predetermined drop or number of drops equivalent to a
desired quantity of coating material. Drop-on-demand also refers to
jetting when a sequence of drops is released. One example of
"drop-on-demand" is the piezo drop-on-demand technology such as
that manufactured by Ink Jet Technology, Inc. of San Jose, Calif.
which provides applicators for a wide variety of coating
applications. Such micro-machined ceramic designs are robust and
chemically inert to almost every kind of fluid and coating and are
compatible with a wide range of fluids with extreme pH values or
strong solvent characteristics. Non-Newtonian fluids are also
compatible with such devices due to the internal design of the
applicator allowing laminar flow of the fluid. With a built in
heater and high temperature operating potential, piezo
drop-on-demand applicators are compatible with a wide variety of
coating materials.
[0005] The term "detector" or "detecting" refers to any device or
method which uses energy, such as magnetic, electrical, heat,
light, etc. to determine whether a target at a desired location on
the prosthesis has been located and signals the applicator to
drop-on-demand or marks the location as one to be coated. The
detector does not determine the location of the applicator relative
to the target to provide feedback for positioning the applicator.
The detector determines the points on the coordinate table for
desired locations on the prosthesis by providing signals for the
applicator controller that are immediately used or stored as
coordinate tables. Examples of detectors are light sensitive
devices such as CCD area cameras, CCD line cameras, high-resolution
CMOS area cameras, or devices that can capture light reflected or
transmitted by the prosthesis, and electrically sensitive devices
such as capacitance detectors.
[0006] The term "applicator" or "applying" refers to any
configuration, apparatus, or method for positioning a coating
material to a surface from a reservoir such as a point source
including but not limited to a nozzle, a dispenser, or tip, or a
multipoint source. An example of an applicator is a drop-on-demand
ink-jet.
[0007] The term "on-the-fly" refers to translation and
drop-on-demand delivery that is synchronous or close to
synchronous, and/or simultaneous or close to simultaneous. Unlike
freestyle movement which requires stopping for validation of
preceding and subsequent movement with relation to the prosthesis,
on-the-fly continues to next movement without validation step. FIG.
13 illustrates an example of on-the-fly drop-on-demand with an
embodiment where the axis of rotation 700 is stationery and
applicator is moving in the Z axis. A servo controller 705 directs
the Z drive 710 which is coupled to applicator 725 while monitoring
the velocity and location of the applicator 725 via feedback device
715. The servo controller 705 keeps the Z drive 710 within
predetermined limits of the required velocity and signals the
applicator controller 720 to activate the drop-on-demand applicator
using data from feedback device 715 with reference to coordinates
from the pre-scan by a detector determining points to be coated. In
this procedure the validation of the Z position of the applicator
725 is done in real-time by the servo controller 705. The servo
controller 705 interacts with the axis of rotation to determine the
next location based on the last location and the time which it
takes Z drive 710 to move applicator 725 to the next location.
Feedback device 715 provides feedback that is an internal
servo-based logic procedure and is not connected to the actual
location relative to the prosthesis and therefore does not become a
validation step as discussed above. In alternative embodiments, the
servo controller 705, Z drive 710, Z location feedback device 715,
the applicator controller 720, and the applicator 725 can be all be
bundled into the application control module (not shown).
[0008] The term "freestyle" refers to movement of an applicator
over a portion of a prosthesis to be coated that requires
validation through a predetermined user selected pattern and/or a
feedback loop of applicator position relative to the portion of the
prosthesis to be coated. Validation is done prior to delivery of
the coating material. In one embodiment, freestyle movement moves
the applicator over a predetermined position based on a user
selected pattern. The position of the applicator is verified
relative to the prosthesis and a new location is calculated. The
applicator is moved to a new and more accurate location. The
applicator delivers the coating material and then moves to the next
predetermined location based on the user selected pattern.
[0009] It is noted that, as used in this specification and the
appended claims, the singular forms "a," "an," and "the" include
plural referents unless expressly and unequivocally limited to one
referent. Thus for example, reference to "an applicator" includes
two or more applicators, but "n is an integer from 1 to 60" means
that n is one integer because that is limited to one integer. Also
noted that as used herein, the term "polymer" is meant to refer to
oligomers, homopolymers, and copolymers. The term "therapeutic
agent" is meant to refer to drugs, therapeutic materials,
diagnostic materials, inerts, active ingredients, and inactive
ingredients.
[0010] For the purposes of this specification and appended claims,
unless otherwise indicated, all numbers expressing quantities of
ingredients or percentages or proportions of other materials,
reaction conditions, and so forth used in the specification and
claims are to be understood as being modified in all instances by
the term "about." Accordingly, unless indicated to the contrary,
the numerical parameters set forth in the following specification
and attached claims are approximations that may vary depending upon
the desired properties sought to be obtained by the present
invention. At the very least, and not as an attempt to limit the
application of the doctrine of equivalents to the scope of the
claims, each numerical parameter should at least be construed in
light of the number of reported significant digits and by applying
ordinary rounding techniques.
[0011] Notwithstanding that the numerical ranges and parameters
setting forth the broad scope of the invention are approximations,
the numerical values set forth in the specific examples are
reported as precisely as possible. Any numerical value, however,
inherently contains certain errors necessarily resulting from the
standard deviation found in their respective testing measurements.
Moreover, all ranges disclosed herein are to be understood to
encompass any and all subranges subsumed therein. For example, a
range of "1 to 10" includes any and all subranges between (and
including) the minimum value of 1 and the maximum value of 10, that
is, any and all subranges having a minimum value of equal to or
greater than 1 and a maximum value of equal to or less than 10,
e.g., 5.5 to 10.
BACKGROUND OF THE INVENTION
[0012] The practice of coating implantable medical devices with a
synthetic or biological active or inactive agent is known. Numerous
processes have been proposed for the application of such a coating.
Soaking or dipping the implantable device in a bath of liquid
medication is suggested by U.S. Pat. No. 5,922,393 to Jayaraman,
soaking in an agitated bath, U.S. Pat. No. 6,129,658 to Delfino et
al. Devices introducing heat and/or ultrasonic energy in
conjunction with the medicated bath are disclosed in U.S. Pat. Nos.
5,891,507 to Jayaraman and 6,245,4 BI to Alt. The device of U.S.
Pat. No. 6,214,1 BI to Taylor et al. suggest spraying the
medication by way of pressurized nozzles.
[0013] Initially such coating were applied at the time of
manufacture. For various reasons such as the short shelf life of
some drugs combined with the time span from manufacture to
implantation and the possible decision of the medical staff
involved concerning the specific drug and dosage to be used based
on the patient's at the time of implantation, a need has arisen for
technologies which permit applying a coating just prior to
implantation. Wrapping the implantable device with medicated
conformal film is disclosed in U.S. Pat. No. 6,309,380 BI to Larson
et al. Dipping or soaking in a medicated bath just prior to
implantation are suggested in U.S. Pat. Nos. 5,871,436 to Eury,
6,6,454 to Berg et al., and 6,1171,232 BI to Papandreou et al. U.S.
Pat. No. 6,3,551 BI to Wu provides a bathing chamber for use with
specific implantable device such as the stent deployed on the
balloon of a catheter (FIG. 1).
[0014] Each of the methods and devices intended for use just prior
to implantation, listed above, deposit the coating material onto
any and all surfaces that are exposed to the coating. This may
result in depositing coating material on surfaces on which the
coating is unwanted or undesirable. Further, the coating may crack
or break away when the implantable is removed from the implantation
apparatus. An example of this would be a stent deployed on a
catheter balloon. As the balloon is inflated and the stent is
expanded into position, the coating may crack along the interface
between the stent and the balloon. These cracks may lead to a
breaking away of a portion of the coating from the stent itself.
Similar problems can occur in cases where the coating technique
fails to prevent inadvertent overlapping with the edges (e.g.,
internal surfaces along the edges) of various devices (e.g., struts
of stents). This, in turn, may affect the medicinal effectiveness
of the coating, and negatively affect the entire medical
procedure.
[0015] It is known to use Ink-Jet technology to apply a liquid to
selected portion of a surface. In the paper "Applications of
Ink-Jet Printing Technology to BioMEMS and Microfluidic Systems,"
presented at the SPIC Conference on Microfluidics and BioMEMS,
October, 01, the authors, Patrick Cooley, David Wallace, and Bogdan
Antohe provide a fairly detailed description of Ink-Jet technology
and the range of its medically related applications
(http://www.microfab.compapers/papers_pdf/spie
biomems_O1_reprint.pdf).
[0016] A related device is disclosed in U.S. Pat. No. 6,001,311 to
Brennan, which uses a moveable two-dimensional array of nozzles to
deposit a plurality of different liquid reagents into receiving
chambers. In the presentation of Cooley and the device of Brennan,
the selective application of the material is based on an objective
predetermined location of deposit rather that on a "subjective
placement" as needed to meet the requirements of a specific
application procedure. With regard to the application of coatings
applied to medical devices with inkjet applicators, while it is
possible to coat only a chosen portion of a device, such as only
the stent mounted on a catheter, but not the catheter itself. This
type of procedure using current technologies may, however, require
providing complex data files, such as a CAD image of the device to
be coated, and insuring that the device be installed in the coating
apparatus in a precise manner so as to be oriented exactly the same
as the CAD image.
[0017] Other systems which use ink-jet applicators apply the
coating with a "freestyle" procedure. The freestyle points are
determined by a preprogrammed user selected pattern that is unique
to the particular shape or contour for the type of prosthesis and
the desired coating to be achieved, much like a vector based
printing approach. The ink-jet nozzle or prosthesis move in
three-dimensionally with the aid of a motion control system. The
motion control system enables the ink-jet nozzle to move over the
portions of the prosthesis to be sprayed. Alternatively, a
real-time picture can be taken with a camera to determine the
position of the ink-jet nozzle in relation to the prosthesis. Based
upon the feedback of nozzle location, the ink-jet applicator can be
controlled by activating the spray, moving the ink-jet nozzle,
and/or moving the prosthesis to adjust to the pattern to better
conform with the actual prosthesis.
[0018] This type of system is particularly inefficient because the
preprogrammed user selected pattern fails to accommodate inherent
variability in the surface of the prosthesis. In one non-limiting
embodiment, for example, a stent crimped around a balloon catheter
will not be crimped such that it has the same surface each time.
The crimping cannot be determined from the factory according to the
manufacturer's specifications of the stent. Further, using this
type of feedback loop serves merely as a "first impression" to
control the spraying, nozzle position, and/or prosthesis position,
and freestyle systems consequently increase the time required to
apply the coating. In the operational theatre, this is undesired
because many types of coatings (e.g., paclitaxel, rapamycin, or
several other pharmaceutical compounds or bioactive agents) have to
be applied to the stent crimped on the balloon catheter immediately
prior to surgery.
[0019] The significance of delivering drug-loaded prostheses may
offer savings benefit in time and cost. Studies have been conducted
to show the importance of delivering the correct drug dose density
on coronary stents to prevent restenosis by application of
paclitaxel or rapamycin. Kandazari, David E. et al., Highlights
from American Heart Association Annual Scientific Sessions 2001:
Nov. 11 to 14, 2001, American Heart Journal 143 (2), 217-228, 2002;
Hiatt, Bonnie L. et al., Drug-Eluting Stents for Prevention of
Restenosis: In Quest for the Holy Grail, Catheterization and
Cardiovascular Interventions 55:409-417, 2002; Kalinowski, M. et
al., Paclitaxel Inhibits Proliferation Of Cell Lines Responsible
For Metal Stent Obstruction: Possible Topical Application In
Malignant Bile Duct Obstructions, Investigational Radiology
37(7):399-404, 2002. Other studies have shown how accuracy of dose
related to cytotoxicity of coating drugs. Liebmann, J. E. et al.,
Cytotoxic Studies Of Paclitaxel (Taxol) In Human Tumor Cell Lines,
Br. J. Cancer, 68(6):1104-9, 1993; Adler, L. M. et al., Analysis Of
Exposure Times And Dose Escalation Of Paclitaxel In Ovarian Cancer
Cell Lines, Cancer, 74(7):1891-8, 1994; Regar, E. et al., Stent
Development And Local Drug Delivery, Br. Med. Bulletin, 59:227-48,
2001. See also http://www.tctmd.com/expert-presentations: Farb, A.,
Comparative Pathology Of Drug Eluting Stents: Insights Into
Effectiveness And Toxicity From Animal Lab, CRF Drug-Eluting Stent
Symposium 2002; Grube, E., Taxol-Eluting Stent Trials, ISET 2002
Miami Beach, Mar. 19-23, 2002 (The effect of taxol on the edges of
the stent and dose response screening); Carter, Andrew J.,
Sirolimus: Pre-Clinical Studies--Evaluation Of Dosing, Efficacy And
Toxicity, TCT September 2001.
[0020] There is therefore a need for a device, and method for its
use, whereby a coating is selectively applied to an implantable
medical device just prior to implantation, such that only the
device or selected portions thereof are coated. It would be
desirable for the device to provide for user selection of coating
material and dosage to be applied, thereby providing choices as to
the specific coating material and dosage to be applied based on the
specific needs of the patient at the time of implantation. It would
be further desirable for the device to provide a sterile
environment in which the coating is applied and the device is
suitable for use in an operating theater.
[0021] Finally, a method and apparatus for coating a prosthesis is
desired that will reduce the time of coating by coating the
prosthesis "on the fly" without having to stop at each point to
apply the coating.
SUMMARY OF THE INVENTION
[0022] The present invention is a method and device, which is
suitable for use in an operating theater just prior to
implantation, for selectively applying a medical coating to an
implantable medical device, for example a stent.
[0023] According to the teachings of the present invention there is
provided, a coating device for selectively applying a coating to
surfaces of an object, the device applying the coating based upon
optical properties of the surfaces such that the coating is applied
to surfaces of a first type and is not applied to surfaces of a
second type, the first type of surface being optically
distinguishable from the second type of surface, the coating device
comprising: at least one object-holding element configured to hold
the object while a coating is applied; at least one optical
scanning device deployed so as to scan at least a portion of the
object, the optical scanning device configured so as to produce
output indicative of the types of surfaces of the object; at least
one coating applicator deployed so as to deposit a fluid so as to
coat at least a portion of the object; at least one fluid delivery
system in fluid communication so as to supply the fluid to the
coating applicator; a processing unit being responsive at least to
the output so as to selectively activate the coating applicator,
thereby applying the coating substantially only to surfaces of the
first type; and a drive system configured so as to provide relative
motion between the surface of the object and the coating
applicator, and between the surface of the object and the optical
scanning device.
[0024] According to a further teaching of the present invention,
the drive system is configured so as to rotate the object-holding
element about an axis perpendicular to a direction of application
of the coating applicator.
[0025] According to a further teaching of the present invention,
the at least one object-holding element is implemented as two
object-holding elements configured so as to simultaneously support
the object at two different regions along a length of the
object.
[0026] According to a further teaching of the present invention,
the two object holding elements are mechanically linked so as to
rotate synchronously about a single axis, the axis being
perpendicular to a direction of application of the coating
applicator.
[0027] According to a further teaching of the present invention,
the at least one coating applicator includes a pressure-pulse
actuated drop-ejection system with at least one nozzle.
[0028] According to a further teaching of the present invention, a
spatial relationship between the coating applicator and the object
is variable.
[0029] According to a further teaching of the present invention,
the spatial relationship is varied along a first axis that is
parallel to a direction of application of the coating applicator,
and a second axis that is perpendicular to the direction of
application of the coating applicator.
[0030] According to a further teaching of the present invention,
the coating applicator is displaceable relative to the
object-holding element, the displacement being along the first axis
and the second axis, thereby varying the spatial relationship.
[0031] According to a further teaching of the present invention,
both the coating applicator and the optical scanning device are
deployed on a displaceable applicator base, displaceable relative
to the object-holding element, the displacement being along the
first axis and the second axis, thereby varying the spatial
relationship.
[0032] According to a further teaching of the present invention,
the at least one coating applicator is implemented as a plurality
of coating applicators and the at least one fluid delivery system
is implemented as an equal number of fluid delivery systems, each
fluid delivery system supplying a different fluid coating material
to the coating applicator with which the each fluid delivery system
is in fluid communication.
[0033] According to a further teaching of the present invention,
the object is a catheter that includes a balloon portion on which a
stent is deployed, such that the stent is a surface of the first
type and the balloon is a surface of the second type surface.
[0034] According to a further teaching of the present invention,
the processing unit is responsive to an indication of the relative
motion so as to change operational parameters of the coating device
as required.
[0035] According to a further teaching of the present invention,
the object-holding element, the coating applicator, the optical
scanning device, the drive system and at least a portion of the
fluid delivery system are deployed within a housing that includes
an application compartment.
[0036] According to a further teaching of the present invention,
the housing includes a base housing section and a detachable
housing section.
[0037] According to a further teaching of the present invention,
the application compartment is defined by portions of both the base
housing section and the detachable housing section.
[0038] According to a further teaching of the present invention,
the base housing section includes the coating applicator, at least
a portion of the fluid delivery system, the optical scanning device
and the processing unit and at least a first portion of the drive
system, and the detachable housing section includes the
object-holding element and at least a second portion of the drive
system.
[0039] According to a further teaching of the present invention,
the base housing section includes at least one fluid delivery
system.
[0040] According to a further teaching of the present invention,
the detachable housing section is disposable.
[0041] According to a further teaching of the present invention,
the application compartment is a substantially sterile
environment.
[0042] According to a further teaching of the present invention,
the coating applicator, and the fluid delivery system are included
in a removable sub housing, the removable sub-housing being
deployed with in the application compartment and the removable
housing being detachably connected to the processing unit.
[0043] There is also provided according to the teachings of the
present invention, a coating device for selectively applying a
coating to surfaces of an object, the device applying the coating
based upon optical properties of the surfaces such that the coating
is applied to surfaces of a first type and is not applied to
surfaces of a second type, the first type of surface being
optically distinguishable from the second type of surface, the
coating device comprising: a) a housing which includes an
application compartment; b) at least one object holding element
deployed within the application compartment, the object holding
element configured to hold the object to which a coating is
applied; c) a displaceable applicator base deployed within the
application compartment, the applicator base including: i) at least
one coating applicator aligned so as to deposit a fluid whereby at
least a portion of the object is coated; and ii) at least one
optical scanning device deployed so as to scan at least a portion
of the object, the optical scanning device configured so as to
produce scanning output indicative of the different types of
surfaces of the object, the displacement of the applicator base
resulting in a variance of a spatial relationship between the
coating applicator base and the object; d) at least one fluid
delivery system in fluid communication so as to supply the fluid to
the coating applicator; e) a processing unit being responsive at
least to the output so as to selectively activate the coating
applicator, thereby applying the coating substantially only to
surfaces of the first type; and f) a drive system configured so as
to provide relative motion between the surface of the object and
the applicator base.
[0044] According to a further teaching of the present invention,
the housing includes a base housing section and a detachable
housing section.
[0045] According to a further teaching of the present invention,
the application compartment is defined by portions of both the base
housing and the detachable housing section.
[0046] According to a further teaching of the present invention,
the base housing section includes the displaceable applicator base,
at least a portion of the fluid delivery system, and the processing
unit, and at least a first portion of the drive system, and the
detachable housing section includes the object holding element and
at least a second portion of the drive system.
[0047] According to a further teaching of the present invention,
the base housing section includes at least one fluid delivery
system.
[0048] According to a further teaching of the present invention,
the detachable housing section is disposable.
[0049] According to a further teaching of the present invention,
the drive system is configured so as to rotate the object-holding
element about an axis perpendicular to a direction of application
of the coating applicator.
[0050] According to a further teaching of the present invention,
the at least one object-holding element is implemented as two
object-holding elements configured so as to simultaneously support
the object at two different regions along a length of the
object.
[0051] According to a further teaching of the present invention,
the two object holding elements are mechanically linked so as to
rotate synchronously about a single axis, the axis being
perpendicular to a direction of application of the coating
applicator.
[0052] According to a further teaching of the present invention,
the at least one coating applicator includes a pressure-pulse
actuated drop-ejection system with at least one nozzle.
[0053] According to a further teaching of the present invention,
the at least one fluid delivery system is deployed in the base
housing.
[0054] According to a further teaching of the present invention,
the at least one coating applicator is implemented as a plurality
of coating applicators and the at least one fluid delivery system
is implemented as a like number of fluid delivery systems, each
fluid delivery system supplying a different fluid coating material
to the coating applicator with which the each fluid delivery system
is in fluid communication.
[0055] According to a further teaching of the present invention,
the coating applicator, and the fluid delivery system are included
in a removable subhousing, the removable sub-housing being
detachably connected to the displaceable applicator base.
[0056] According to a further teaching of the present invention,
the spatial relationship is varied along two axes, a first axis
that is parallel to a direction of application of the coating
applicator, and a second axis that is perpendicular to the
direction of application of the coating applicator.
[0057] According to a further teaching of the present invention,
the object is a catheter that includes a balloon portion on which a
stent is deployed, such that the stent is a surface of the first
type and the balloon is a surface of the second type.
[0058] According to a further teaching of the present invention,
the processing unit is responsive to an indication of the relative
motion so as to change operational parameters of the coating device
as required.
[0059] There is also provided according to the teachings of the
present invention, a coating method for selectively applying a
coating to surfaces of an object, the method applying the coating
based upon optical properties of the surfaces such that the coating
is applied to surfaces of a first type and is not applied to
surfaces of a second type, the first type of surface being
optically distinguishable from the second type of surface, the
coating device comprising: generating relative movement between the
object and at least one optical scanning device and at least one
coating applicator; optically scanning at least a portion of the
object by use of the at least one optical scanning device so as to
produce output indicative of the different types of surfaces of the
object; responding to the output by selectively activating the
coating applicator, thereby applying the coating substantially only
to surfaces of the first type.
[0060] According to a further teaching of the present invention,
the relative movement includes rotating the object about an axis
perpendicular to a direction of application of the coating
applicator.
[0061] According to a further teaching of the present invention,
there is also provided simultaneously supporting the object at two
different regions along a length of the object.
[0062] According to a further teaching of the present invention,
the selective activation includes selectively activating a
pressure-pulse actuated drop ejection system with at least one
nozzle.
[0063] According to a further teaching of the present invention,
the selective activation includes selectively activating a
pressure-pulse actuated drop ejection system with at least one
nozzle that is included in a removable sub housing, the removable
sub-housing further including a fluid delivery system in fluid
communication so as to supply coating material to the coating
applicator.
[0064] According to a further teaching of the present invention,
the applying is preformed by selectively activating one of a
plurality of coating applicators, wherein the at least one coating
applicator implemented as the plurality of coating applicators,
each of the plurality of coating applicators applying a different
coating.
[0065] According to a further teaching of the present invention,
the applying is preformed by selectively activating, in sequence,
the plurality of coating applicators, thereby applying a plurality
of layered coats, each one of the plurality of layered coats being
of a coating material that is different from adjacent layered
coats.
[0066] According to a further teaching of the present invention,
responding to the output includes the output being indicative of a
balloon portion of catheter and a stent deployed on the balloon,
such that the stent is a surface of the first type and the balloon
is a surface of the second type.
[0067] According to a further teaching of the present invention,
responding to the output includes the output being indicative only
of a surface of the first type thereby applying the coating to
substantially the entire surface of the object.
[0068] According to a further teaching of the present invention,
there is also provided varying a spatial relationship between the
coating applicator and the object.
[0069] According to a further teaching of the present invention,
the varying is along two axes, a first axis that is parallel to a
direction of application of the coating applicator, and a second
axis that is perpendicular to the direction of application of the
coating applicator.
[0070] According to a further teaching of the present invention,
the varying is accomplished by displacing the coating
applicator.
[0071] According to a further teaching of the present invention,
the varying is accomplished by varying the spatial relationship
between the object and a displaceable applicator base upon which
the at least one coating applicator and the at least one optical
scanning device are deployed.
[0072] According to a further teaching of the present invention,
controlling the varying is accomplished by the processing unit.
[0073] According to a further teaching of the present invention,
there is also provided responding to an indication of the relative
motion so as to change operational parameters of the coating device
as required.
[0074] According to a further teaching of the present invention,
generating relative movement, the optically scanning at least a
portion of the object, and the selectively activating the coating
are preformed within a housing.
[0075] According to a further teaching of the present invention,
there are multiple applicators provided for coating injection to
achieve better performance.
[0076] According to a further teaching of the present invention,
there is a cleaning material container provided to clean the
applicator at the end of the application process. The cleaning
material is compatible with the drug being used.
[0077] According to a further teaching of the present invention,
there is a cover provided on the front surface of the applicator at
the end of the use.
[0078] According to a further teaching of the present invention, a
wiper is provided to clean the applicator surface.
[0079] According to a further teaching of the present invention, a
metering gauge is provided to measure the quantity of coating
material applied through the applicator.
[0080] According to a further teaching of the present invention,
optical scanning is provided by the use of a light source that can
scan intensity in white, black or other colors.
[0081] According to a further teaching of the present invention,
other application, dispensing, and depositing methods can be used
with the features of the present invention.
[0082] According to a further teaching of the present invention, a
method for coating comprises (a) providing a prosthesis having
identifiable features; (b) pre-scanning the prosthesis prior to
coating to identify the features and to obtain coating coordinates
for the features; and (c) depositing a coating material at desired
regions of the prosthesis as a function of the coordinates.
[0083] According to a further teaching of the present invention,
the method comprises (d) determining paths between the coating
coordinates for an applicator to deposit the coating material.
[0084] According to a further teaching of the present invention,
the method comprises (e) determining a sequence for the coating
coordinates.
[0085] According to a further teaching of the present invention,
the method comprises (f) determining vectors between the coating
coordinates in the sequence.
[0086] According to a further teaching of the present invention,
the method comprises (d) determining a predetermined path
independent of the coating coordinates.
[0087] According to a further teaching of the present invention,
the predetermined path covers a surface area of the prosthesis,
wherein the surface area comprises the coating coordinates.
[0088] According to a further teaching of the present invention,
the predetermined path is a function of the overall contour or
geometric shape of the prosthesis.
[0089] According to a further teaching of the present invention,
the method comprises (d) post-scanning the prosthesis after
coating.
[0090] According to a further teaching of the present invention,
the post-scanning comprises rotating the prosthesis and detecting
of the coated prosthesis.
[0091] According to a further teaching of the present invention,
the pre-scanning comprises rotating the prosthesis and detecting of
the prosthesis.
[0092] According to a further teaching of the present invention,
detecting comprises detecting energy from the identifiable features
of the prosthesis.
[0093] According to a further teaching of the present invention,
the pre-scanning comprises analyzing the images for edges
associated with the prosthesis.
[0094] According to a further teaching of the present invention,
the pre-scanning comprises determining the coating coordinates from
the edges.
[0095] According to a further teaching of the present invention,
detecting comprises capturing energy transmitted around
identifiable features of the prosthesis.
[0096] According to a further teaching of the present invention,
pre-scanning comprises analyzing images for the edges associated
with the prosthesis.
[0097] According to a further teaching of the present invention,
pre-scanning comprises determining the coating coordinates from the
edges.
[0098] According to a further teaching of the present invention,
the coating material is chosen from polymers, therapeutic agents,
and mixtures thereof.
[0099] According to a further teaching of the present invention,
the method for coating comprises (a) providing a prosthesis; (b)
pre-scanning the prosthesis prior to coating to obtain coating
coordinates for the prosthesis; (c) coating the prosthesis at the
coating coordinates; and (d) post-scanning the prosthesis after
coating.
[0100] According to a further teaching of the present invention,
the coating comprises translating the coating applicator and
drop-on-demand delivery of a quantity of coating from a coating
applicator, wherein said translating and said delivery are
on-the-fly.
[0101] According to a further teaching of the present invention,
the coating process comprises raster type coating step.
[0102] According to a further teaching of the present invention,
the coating process comprises vector type coating step.
[0103] According to a further teaching of the present invention,
pre-scanning comprises rotating the prosthesis and detecting of the
prosthesis.
[0104] According to a further teaching of the present invention,
pre-scanning comprises rotating a detector and detecting of the
prosthesis.
[0105] According to a further teaching of the present invention,
post-scanning comprises rotating the prosthesis and detecting of
the coated prosthesis.
[0106] According to a further teaching of the present invention,
post-scanning comprises rotating a detector and detecting of the
coated prosthesis.
[0107] According to a further teaching of the present invention,
detecting comprises capturing energy from the prosthesis or
capturing energy transmitted around the prosthesis.
[0108] According to a further teaching of the present invention,
pre-scanning and the post-scanning comprises analyzing the images
for edges of the prosthesis.
[0109] According to a further teaching of the present invention,
pre-scanning comprises determining the coating coordinates from the
edges.
[0110] According to a further teaching of the present invention,
the analyzing comprises comparing images from the pre-scanning and
the post-scanning.
[0111] According to a further teaching of the present invention,
analyzing comprises identifying coating errors.
[0112] According to a further teaching of the present invention,
the method comprising repeating the coating step to re-coat the
prosthesis at coordinates associated with detected coating
errors.
[0113] According to a further teaching of the present invention,
the method comprises assigning a coating quality approval to the
coated prosthesis.
[0114] According to a further teaching of the present invention,
analyzing comprises optically distinguishing a first type of
surface from a second type of surface.
[0115] According to a further teaching of the present invention,
analyzing comprises rendering a three-dimensional shape from the
images.
[0116] According to a further teaching of the present invention,
analyzing comprises identifying pigment in a coating applied to the
prosthesis.
[0117] According to a further teaching of the present invention,
coating comprises jetting with hot air, wherein the hot air
evaporates a volatile solvent in a coating material.
[0118] According to a further teaching of the present invention,
coating comprises directing infrared radiation, wherein the
infrared radiation evaporates a volatile solvent in a coating
material.
[0119] According to a further teaching of the present invention,
the coating material is chosen from polymers, therapeutic agents,
and mixtures thereof.
[0120] According to a further teaching of the present invention,
the method for coating comprises (a) providing a prosthesis having
identifiable features; (b) determining a predetermined path
independent of the features; and (c) coating the prosthesis at
desired regions, wherein said regions are a function of the
features.
[0121] According to a further teaching of the present invention,
the predetermined path covers a surface area of the prosthesis,
wherein the surface area comprises the desired regions.
[0122] According to a further teaching of the present invention,
the predetermined path is a function of the overall contour or
geometric shape of the prosthesis.
[0123] According to a further teaching of the present invention,
the coating process comprises a raster type coating step.
[0124] According to a further teaching of the present invention,
the coating material is chosen from polymers, therapeutic agents,
and mixtures thereof.
[0125] According to a further teaching of the present invention,
the apparatus for coating comprises an applicator for applying a
coating material to a prosthesis; a detector for scanning the
prosthesis; and an applicator controller connected to the detector
and the applicator, wherein the applicator controller is adapted to
on-the-fly coating.
[0126] According to a further teaching of the present invention,
the prosthesis comprises identifiable features for which the
detector provides coating coordinates for the applicator
controller.
[0127] According to a further teaching of the present invention,
the applicator controller is adapted to determine paths between the
coating coordinates for the applicator.
[0128] According to a further teaching of the present invention,
the system for coating comprises (a) means for providing a
prosthesis having identifiable features; (b) means for pre-scanning
the prosthesis prior to coating to identify the features and to
obtain coating coordinates for the features; and (c) means for
applying a coating material at desired regions of the prosthesis as
a function of the coordinates.
[0129] According to a further teaching of the present invention,
the system comprising (d) means for determining paths between the
coating coordinates for an applicator.
[0130] According to a further teaching of the present invention,
the system comprising (e) means for determining a sequence for the
coating coordinates.
[0131] According to a further teaching of the present invention,
the system comprising (f) means for determining vectors between the
coating coordinates in the sequence.
[0132] According to a further teaching of the present invention,
the system comprising (d) means for determining a predetermined
path independent of the coating coordinates.
[0133] According to a further teaching of the present invention, a
computer program product for coating comprises computer-readable
media having computer-readable code, the computer program product
comprising the following computer-readable program code for
effecting actions in a computing platform (a) program code for
providing a prosthesis having identifiable features; (b) program
code for pre-scanning the prosthesis prior to coating to identify
the features and to obtain coating coordinates for the features;
and (c) program code for depositing a coating material at desired
regions of the prosthesis as a function of the coordinates.
[0134] According to a further teaching of the present invention,
the computer program comprises (d) program code for determining
paths between the coating coordinates for an applicator.
[0135] According to a further teaching of the present invention,
the computer program comprises (e) program code for determining a
sequence for the coating coordinates.
[0136] According to a further teaching of the present invention,
the computer comprises (f) program code for determining vectors
between the coating coordinates in the sequence.
[0137] According to a further teaching of the present invention,
the computer program product comprising (d) program code for
determining a predetermined path independent of the coating
coordinates.
[0138] According to a further teaching of the present invention,
the applicator control module comprises an applicator adapted to
drop-on-demand a quantity of coating material at a desired location
of a prosthesis; and an applicator controller adapted to on-the-fly
coating.
[0139] According to a further teaching of the present invention,
the applicator controller comprises of a servo controller, a driver
for said applicator, and a location feedback device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0140] The invention is herein described, by way of example only,
with reference to the accompanying drawings, wherein: FIG. 1 is a
cut-away side elevation of a stent coating device constructed and
operative according to the teachings of the present invention.
[0141] FIG. 2 is a cut-away perspective view of the stent coating
device of FIG. 1.
[0142] FIG. 3 is a perspective detail of an alternative
displaceable applicator head constructed and operative according to
the teachings of the present invention, shown here configure with
disposable coating applicators.
[0143] FIG. 4 is a cut-away perspective view of the stent coating
device of FIG. 1, showing the detachable section of the housing
separated from the base section of the housing.
[0144] FIG. 5 is a perspective detail of an upper stent holding
element, constructed and operative according to the teachings of
the present invention.
[0145] FIG. 6 is a side elevation of the stent coating device of
FIG. 1 showing the full length of a catheter being supported by the
support antenna.
[0146] FIG. 7A is a flow chart of a non-limiting embodiment of a
method for coating a stent according to the present invention.
[0147] FIG. 7B is a flow chart of the method known in the art for
coating a stent.
[0148] FIG. 8 is a flow chart of a non-limiting embodiment of the
pre-coating procedure according to the present invention.
[0149] FIG. 9A is a flow chart of a non-limiting embodiment of the
coating procedure according to the present invention.
[0150] FIG. 9B is a flow chart of a procedure for coating a stent
using a pre-selected library.
[0151] FIG. 9C is a flow chart of a procedure for coating a stent
using real-time imaging.
[0152] FIG. 10 is a flow chart of a non-limiting embodiment of the
post-coating procedure according to the present invention.
[0153] FIG. 11 illustrates a detail of a stent on a balloon
catheter, and a blowup perspective of the stent surface to be
coated.
[0154] FIG. 12 illustrates a flow chart of a non-limiting
embodiment of raster coating without the use of pre-scanning or
post-scanning.
[0155] FIG. 13 illustrates a flow chart of an embodiment of
"on-the-fly" translation of the applicator and delivery of the
coating material. In alternative embodiments, the servo controller
705, Z drive 710, and Z location feedback device 715 can be all be
bundled into the application controller 720.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0156] The present invention is a method and device, which is
suitable for use in an operating theater just prior to
implantation, for selectively applying a medical coating to an
implantable medical device, for example a stent.
[0157] The principles and operation of a coating device according
to the present invention may be better understood with reference to
the drawings and the accompanying description.
[0158] By way of introduction, the embodiment discussed herein is a
device for applying a medical coating to a stent deployed on a
catheter, the coating being applied just prior to implantation and
if desired in the operating theater. The use of optical scanning
devices enables a processing unit to distinguish between the
surface area of the stent and the surface area of the catheter. The
processing unit selectively activates the coating applicator so as
to apply the coating to substantially only the stent and not the
balloon or other portion of the catheter. The coating applicator
discussed herein is, by non-limiting example, a pressure-pulse
actuated drop-ejection system with at least one nozzle. A readily
available pressure-pulse actuated drop-ejection system, which is
well suited for the present invention, is a drop-on-demand inkjet
system. It should be noted, however, that any coating application
system that may be selectively activated is within the intentions
of the present invention. While the discussion herein is specific
to this embodiment, which is intended for use in an operating
theater, among other places, this embodiment it is intended as a
non-limiting example of the principals of the present invention. It
will be readily apparent to one skilled in the art, the range of
applications suited to the principals of the present invention.
Even the device described herein, as a non-limiting example, with
minor adaptations to the object-holding element and choice of fluid
coating materials, is well suited for a wide range of objects to
which a coating is applied.
[0159] Referring now to the drawings, as mentioned above, FIG. 1
illustrates a device for applying a coating to a stent 2 that is
deployed on a catheter 4. The coating being applied may be a
synthetic or biological, active or inactive agent. The perspective
view of FIG. 2 is of the same side of the device as FIG. 1, and
therefore when the description of elements of the device will be
better understood, FIG. 2 will be referenced. The catheter 4 is
placed in an application compartment 40 and held in position by a
rotatable catheter-holding base 6 and a rotatable upper
catheter-holding element 8, which are configured for substantially
continued rotation, that is they may complete a plurality of full
360 degree rotations, as required, during the coating process. The
actual rotation may be substantially fully continuous (non-stop) or
intermittent. The upper catheter-holding element will be discussed
in detail below with regard to FIG. 4. The enclosed application
compartment provides a sterile environment in which the coating
process is performed. The rotation of the catheter-holding base and
the upper catheter-holding element is actuated and synchronized by
a motor and gear system that includes gear clusters 12, 14, 16, and
shaft 18 (see also FIG. 2). Alternatively, the gears may be
replaced by drive belts or drive chains. The remaining length of
the catheter is supported by a support antenna 22, as illustrated,
by non-limiting example, in FIG. 6. As noted above, the
object-holding elements may be modified so as to hold any object
suitable for coating according to the teachings of the present
invention.
[0160] The coating is applied by a drop-on-demand inkjet system in
association with an optical scanning device and processing unit. As
the object is rotated by the object-holding element, the optical
scanning device scans the surface of the object. The out-put from
the scanning device is used by the processing unit to determine if
the surface area currently aligned with the coating applicator is
of the type of surface to be coated. When it is determined that the
desired type of surface is aligned with the coating applicator, the
processing unit activates the coating applicator and the coating is
dispensed. The embodiment shown here includes three inkjet coating
applicators 30a, 30b, and 30c, and two optical scanning devices 32a
and 32b. The optical scanning devices may be configured to generate
digital output or an analog signal, which is in turn analyzed by
the processing unit. It should be noted that the number of coating
applicators and scanning devices may be varied to meet design or
application requirements. The three coating applicators and the two
optical scanning devices are mounted on a displaceable applicator
head 34. The position of the applicator head within the application
compartment, and thereby the spatial relationship between the
coating applicator and the stent, or other object being coated, is
regulated by the application control module 36, which is, in turn,
controlled by the processing unit. The change of position of the
applicator head is effected vertically by turning the vertical
positioning screw 60 in conjunction with guide shaft 62, and the
horizontally by turning the horizontal positioning screw 64 in
conjunction with guide shaft 66. The vertical repositioning in
conjunction with the rotation of the object enables the coating
applicator to traverse substantially the entire surface of the
object requiring coating.
[0161] Fluid coating material is stored in three fluid reservoirs
50a, 50b, and 50c (see FIG. 2), and supplied to the respective
coating applicators by the fluid supply hoses 52a, 52b and 52c (see
FIG. 2). In general use, each of the fluid reservoirs contains a
different coating material, thus, each coating applicator will
deposit a different coating material on the stent or other objected
being coated, as required. Further, a plurality of coats may be
applied, each coat being of a different coating material and, if
required, of a different thickness. Thus, at the time of coating, a
single appropriate coating material may be chosen from the
materials provides, or a combination of coatings may be chosen. It
should be noted that while the fluid reservoirs are shown here in a
compartment inside the device housing, this need not always be the
case, and the reservoirs may be external to the housing.
[0162] It should be noted that, alternatively, the inkjet system
may be deployed in a disposable housing that also includes a fluid
reservoir filled with coating material. The fluid reservoir may be
an enclosed volume that is integral to the disposable housing or it
may be a coating filled cartridge that is inserted into a receiving
cavity in the disposable housing. In this case, as illustrated in
FIG. 3, the displaceable applicator head 34 is configured so as to
accept one or more of the disposable housings 36a, 36b, and 36c,
which in turn house inkjet coating applicators 38a, 38b, and 38e
respectively. The fluid reservoirs (not shown) for each applicator
are housed in that portion of the disposable housing that is
deployed within the displaceable applicator head 34.
[0163] FIG. 4 illustrates how the base housing section 70 and the
detachable housing section 72 are interconnected. The two sections
are held together by inserting pins 74, extending from the
detachable housing section, into the corresponding holes 76,
located in the base housing section, and engaging the latch
mechanism 78 with the catch element 80. Detachment of the two
sections is accomplished by pressing the release "button" 84, which
raises the end 82 of the latch thereby releasing the catch element.
The two sections are then pulled apart. As seen here more clearly,
the application compartment is defined by a top, floor and three
walls located in the detachable housing section and one wall on the
base housing section. The detachable housing section is configured
so as to be disposable, or if desired, easily cleaned and
re-sterilized.
[0164] The detail of FIG. 5 shows the components of the upper
catheter-holding element. Extending from substantially the center
of the rotating base plate 90, is a threaded tube 92. This tube is
the external end of the passageway through which the catheter tip
with the stent attached is inserted in order to deploy the stent in
the application compartment of the coating device. The tube is cut
longitudinally several times, to create threaded sections 98, here
six, that are configured so as to flex outward from the center. The
tightening-disk 94, has a correspondingly threaded center hole for
deployment on the tube 92 such that when the tightening-disk is
brought to a position proximal to the base plate, the threaded
sections near the end of the tube will flex outwardly thereby
enlarging the diameter of the opening. The gripping element 96 also
has divergently flexing "fingers" 100. In operation, the gripping
element is deployed around the catheter, which is then passed
through the tube and into the application compartment. Once the
catheter is positioned on the catheter holding base, the gripping
element is at least partially inserted into the opening of the
tube. The tightening-disk 94 is then rotated about the tube, and
thereby brought to a position proximal to the end of the tube, the
outwardly flexing sections of the tube 98 are brought into an
un-flexed state thereby decreasing the diameter of the opening. The
decrease in the diameter of the tube opening pushes the "fingers"
of the gripping element against the catheter, thereby holding the
catheter in place.
[0165] A non-limiting example of the stent coating process as
accomplished by the above describe device would be as follows:
[0166] 1. The fluid reservoirs are filled with the required fluid
coating materials.
[0167] 2. The parameters of the coating are inputted into the
processing unit. The parameters may include, by non-limiting
example, the coating material to be applied, the thickness of the
coating, number of multiple layers of different coating material,
the order in which the layered materials are to be applied, and the
thickness of each layer. The parameters may be determined by the
physician at the time the coating is applied or the parameters may
be pre-set, such as those determined by medical regulations. In the
case of pre-set parameters, the physician would simply input a
"start" command.
[0168] 3. The catheter is positioned in the application compartment
and the upper catheter-holding element is tightened.
[0169] 4. As the catheter rotates, the optical scanning device
scans the surface of the catheter, to distinguish between the
surface of the balloon and the surface of the stent.
[0170] 5. When a portion of the surface of the stent is detected
and determined to be in alignment with the appropriate coating
applicator, the processing unit selectively activates the
applicator, thereby ejecting the necessary amount of coating
material, which is deposited substantially only on the surface of
the stent.
[0171] 6. Throughout the coating process, the position of the
applicator head is adjusted as required. This adjustment may bring
the coating applicator closer to, or farther away from, the surface
of the stent, and it may adjust the vertical deployment of the
coating applicator, thereby allowing different areas of the surface
of the stent to be coated. Further, if a different fluid coating
material is needed for a different layer of the coating, the
coating applicator for that particular coating material may be
brought into appropriate alignment for deposition of the new
coating material on the stent.
[0172] 7. When the coating process is completed, the catheter with
the now coated stent is removed from the device, and the stent is
ready for implantation.
[0173] 8. The detachable housing section is removed and may be
cleaned and sterilized for re-use, or simply discarded.
[0174] It should be noted that in some cases it may be desirable to
coat substantially the entire surface of the object being coated.
This may be accomplish in at least two ways. The object itself may
have only one type of surface. Alternatively, the scanning device
may be configured so as to provide adjustable scanning sensitivity.
In such a case, the sensitivity of the scanning device may be
adjusted such that the out-put is indicative of only one type of
surface and the processing unit is unable to distinguish between
different types of surfaces.
[0175] The flowchart of FIG. 7A illustrates a process for coating a
prosthesis 102 based on the present invention. In this non-limiting
example, the prosthesis is a stent that is to be coated with a
therapeutic agent. The first step 105 is to place the stent and
therapeutic agent container in the stent coating device. The system
is then ready for processing the stent. The system starts at 110.
The pre-coating procedure 115 collects information in the
processing unit (not shown) of the stent coating device to be used
during the coating procedure 120. The post-coating procedure 125
verifies that the stent has been properly coated and should be
approved for removal 130. The flowchart of FIG. 7B illustrates the
process for coating stents 140 known in the art. The user selects a
pattern 145 according to the type of stent to be coated and the
pattern of coating to be delivered. The pattern selected varies on
parameters provided by the stent manufacturer and the coating to be
applied. The process starts 150 according to the pattern that has
been selected. The coating procedure 155 applied the coating to the
stent, and once complete, the coated stent 160 is ready for
removal.
[0176] FIG. 8 illustrates the pre-scanning procedure 115. The stent
is pre-scanned 205 prior to the coating procedure 120. In parallel,
the application control module is initialized 200. Initialization
of the application control module comprises finding a specific
point on the stent to begin coating. The pre-scan is analyzed 210
in the processing unit. The analysis determines and compiles the
coating coordinates table 215 to be used to position the
application control module.
[0177] There is a large standard deviation between stents of the
same design, especially after the stent is crimped on the balloon
catheter. The preprogrammed pattern is not helpful to manage these
deviations from the design. Pre-scanning can provide a check for
defects in the stent structure prior to coating. Pre-scanning can
also provide the best positions on to which to spray the coating.
Crimping does not always result in a uniform deformation of the
stent structure. Some portions of the stent may be more densely
packed than other portions. Some intersections of stent struts may
have different angles of incidence. Pre-scanning can provide the
optimal path to follow over the stent surface to be coated. Some
applications require only a portion of the stent to be coated.
Pre-scanning can prevent over-jetting of the coating on a specific
location. Over-jetting can result in inadvertent coating from the
stent on the balloon catheter.
[0178] Scanning can be achieved by a variety of imaging techniques
known in the art of imaging, including but not limited to
photographic, video, infrared, and VCSEL (Vertical Cavity Surface
Emitting Laser) technologies using a variety of detectors. VCSELs
can be used as the detector for optical imaging, and can double as
the applicator itself. Choquette, Kent D., Vertical Cavity Surface
Emitting Lasers--Light for Information Age, MRS Bulletin, pp.
507-511, July 2002. In one non-limiting embodiment, a photograph of
the stent is taken by a detector. The stent is rotated slightly
(e.g., one-half to a few degrees) and then another photograph is
taken, resulting in at least several dozen photographs total. The
detector is focused sufficiently close to the stent to record
enough resolution relative to the coating droplet to be applied. If
the stent is long, the rotation may have to be repeated to capture
the top and bottom of the stent.
[0179] A light source can be positioned on the same side as the
detector or on the opposite side of the detector relative to the
stent. In the embodiment where the light source is on the same side
as the detector, the detector received light reflected by the
stent. The stent appears light in color and the balloon appears
dark in color. In the embodiment where the light source is on the
opposite side of the detector, the detector receives light
transmitted through the balloon and around the stent struts. The
stent appears dark in color and the balloon appears light in color.
The contrast between the light and dark color in both embodiments
can be used for edge analysis. Edge analysis comprises determining
the edges of the stent and finding the center-line of stent surface
to be coated. The edges and center-line determine the coating
coordinates which are collected for each surface of the stent to be
coated in the coating coordinates table.
[0180] In one non-limiting embodiment, the pre-scan is compared to
an index of patterns in the processing unit. This can be used to
confirm the accuracy of the edge analysis and provide a safety
measure for detection of defects in the stent or errors in the edge
analysis.
[0181] Coating coordinates can be interpreted and coded as raster
or vector type of data forms. These data forms describe different
translation of the applicator by the Z driver. Both data forms
comprise using an algorithm to find all the coordinates of the
stent that should be coated and compiling a map of "to be coated
points" or coordinates. Chart 1 illustrates a map of coordinates
showing the point location on Z, as a function of the relative
axial rotation in degrees.
[0182] Vector type coating comprises taking the unique variables
(e.g., Z and rotation), and using another algorithm to select the
shortest distance or otherwise most efficient path to move between
one coating coordinate and the next most proximate coordinate to be
coated. Vector coating can also comprise creating a list of
coordinates in sequential order. Table 1 illustrates a "best pass
algorithm" as a coordinate table correlating location on Z to angle
of rotation for each coordinate.
1TABLE 1 Coordinate no. Z Rotation 1 3 15 2 6 30 3 9 45 4 6 60 5 9
60 6 15 60
[0183] Control software in the processing unit can calculate a set
of movement vectors for the application control module between each
set of sequential coordinates. Vector parameters may comprise
coordinates, .DELTA.z (change in location between two adjacent
points or coordinates on Z axis), .DELTA.rot (change in angle
between coordinates), velocity between the coordinates, etc. Table
2 illustrates vectors that can be calculated from coordinate table
in Table 1. Each vector can have a different velocity associated
with it represented as values a, b, and c. Each vector can have a
difference quantity associated with it represented as values d, e,
f, g, h which may be the same of different. Other parameters can
also be associated with each vector.
2TABLE 2 Vector .DELTA.z .DELTA.rot Velocity Quantity 1-2 3 15 a d
2-3 3 15 a e 3-4 -3 15 a f 4-5 3 0 b g 5-6 6 0 c h
[0184] A raster type coating comprises using an algorithm to find
all the coordinates of the stent that should be coated and
compiling a map of coordinates. This is similar to vector type
coating as is illustrated in Chart 1 above. Raster type coating,
however, also comprises taking the unique variables (e.g., Z and
rotation), and using a different algorithm to calculate and compile
a coordinate table of Z coordinates for each rotation angle in
predetermined increments of rotation. The term "rotation
resolution" refers to the number of increments in rotation angle.
Raster type coating is rotation-resolution-specific. This means
that raster printing is calculated and executed at one specific
rotation resolution, or in a variety of other manipulations
inter-relating the prosthetic item to be coated, the holder for
such prosthetic and the applicator nozzle. Table 3 illustrates a
coordinate table correlating angle of rotation with locations on Z.
These locations: Z1, Z2, Z3, Z4, etc. represent intersections with
the surface of the stent to be coated at each angle of
rotation.
3TABLE 3 ROTATION ANGLE Z1 Z2 Z3 Z4 15 3 9 30 6 20 45 9 60 6 9
15
[0185] Control software in the processing unit can calculate the Z
coordinates for each angular position and direct the application
control module and coating applicator to go to an angular rotation
position and move along Z at a regulated, constant or variable
velocity. While moving along Z, the coating applicator injects at
Z1, Z2, Z3, Z4, etc. After traveling the full length of the stent
along Z, the application control module moves the coating
applicator to the next angle of rotation, changes the direction
along Z (now opposite the previous direction) which the coating
applicator travels. While traveling in this new direction, the
coating applicator injects over the next Z locations.
[0186] Additional raster-based manipulations could include, for
example, rotational movements of the stent in conjunction with
serial, stepped Z-axis movements, or "screw-like" movements along a
helical path of the stent accomplished by simultaneous movement of
rotation and stepped Z-axis movements as is described below. In any
event, the raster-based coating process results in motion with
respect to the stent and applicator which covers the entire
prosthetic, while the vector-based coating process only travels
over the "to be coated" surfaces. Consequently, the vector-based
approach is object dependent, while the raster-based approach is
simply system defined.
[0187] FIG. 11 illustrates a stent 2 on a balloon catheter 4. The
axis of rotation, Z, is also the axis of symmetry 500 for the
stent. The magnified window of FIG. 11 shows the stent structure to
be coated 505 and gaps in stent structure where balloon catheter 4
is not covered by the stent. During scanning, the stent is rotated
in incremental angles according to the rotation resolution to
generate the coordinate table. During coating, the application
control module rotates the stent in the same incremental angles and
positions the coating applicator at the Z locations to coat the
stent. In one non-limiting embodiment, the coating applicator can
drop-on-demand a coating with accuracy as is known in the art of
ink-jet printing.
[0188] The flowchart of FIG. 9A illustrates an embodiment of the
coating procedure 120. The present embodiment contemplates raster
coating accomplished by longitudinal movement of the applicator
along the length of a cylindrical body and point-to-point ("PTP")
rotation of the cylindrical body or applicator around the
circumference of the cylindrical body. An initial angle of rotation
is selected 300. The application control module moves the coating
along the Z axis 310, while controlling drop-on-demand at Z
coordinate 315, and receiving the next coating coordinate from the
processing unit 305. Once the coating applicator has moved along
the length of the stent, the application control module changes the
direction of travel along the Z axis of the coating applicator 320,
and rotates the stent to the next angle of rotation 325. This
process is repeated by repeating steps 310-325 until the stent has
been coated according to the coordinate table. In one non-limiting
embodiment, the change in incremental angle of rotation can be
one-half of one degree and can require up to 500 rotations of the
stent to coat each point in the coordinate table. Multiple coatings
can be applied sequentially or simultaneously by repeating the
steps and/or changing the coating reservoir.
[0189] In another embodiment, raster coating can be accomplished by
coating along the circumferential rotation of the cylindrical body
or applicator with PTP longitudinal movement of the applicator
along the length of the cylindrical body. In another embodiment,
raster coating can be accomplished by both circumferential rotation
of the cylindrical body or applicator and longitudinal movement of
the applicator with PTP longitudinal movement of the applicator or
PTP rotation of the cylindrical body or applicator along the
circumference of the cylindrical body. This embodiment results in a
spiral or "screw" predetermined path.
[0190] In other embodiments, raster coating can be accomplished by
following a predetermined path to apply coating material at desired
locations of the prosthesis without regard to the pattern of the
coating. In some embodiments, this predetermined path can
incorporate the overall contour or geometrical shape of the
prosthesis to efficiently cover the surface area which includes the
desired locations to be coated. In some certain embodiments,
efficiency can be realized by utilizing axes of symmetry or other
geometrical simplifications of the overall contour of the
prosthesis.
[0191] The flowchart of FIG. 9B illustrates the coating procedure
155 which is known in the art. The coating nozzle is in an initial
position 330. The controller receives coordinates from a user
selected pattern 335. The controller interprets the coordinates
into X, Y, and Z constant velocity movement 340, and positions the
nozzle to jet by controlling the nozzle delivery 350, the nozzle
motion 355, and/or the stent motion 360. The nozzle then
drop-on-demand 365. Then the nozzle travels over the stent to the
next coordinate based on the user selected patter.
[0192] The flowchart of FIG. 9C illustrates the coating procedure
155 which is known in the art also begins with the coating nozzle
at an initial position 330. A picture of the nozzle, stent, and/or
coating is taken 342. The picture is analyzed using vision software
345. The controller interprets the picture and positions the nozzle
to jet by controlling the nozzle delivery 350, the nozzle motion
355, and/or the stent motion 360. The nozzle then drop-on-demand
365. This requires real-time imaging and adjustment prior to
coating portions of the stent.
[0193] The flowchart in FIG. 10 illustrates an embodiment of the
present invention including a post-coating procedure 125. The
coating applicator is held in stand-by mode 400, while the stent is
post-scanned 405, scan analysis 410 analyzes the coated stent for
mistakes in coating and provides coating quality assurance and
approval 420. If approved, the stent coating is complete 130. In
one non-limiting embodiment, the coating comprises pigment to
facilitate scan analysis by differentiating between the stent and
coating. In one non-limiting embodiment, the pre-scan images can be
used for the approval of the stent. Post-scanning facilitates
locating coordinates where coating was not applied because of
jetting problems. Post-scanning also facilitates in locating
leakage or "overspray" points where the coating has leaked from the
stent onto the balloon catheter.
[0194] The flow chart in FIG. 12 illustrates an embodiment of
raster coating without pre-scanning or post-scanning. The method
for coating a prosthesis 600, begins with setting 605 the
predetermined length L, incremental linear movement .DELTA.x, and
incremental angular movement .DELTA..theta., along with a reference
point recognized as a characteristic feature of the prosthesis. The
detector is turned on 610. The detector and applicator move 615
linearly from the reference point an incremental distance .DELTA.x
and .DELTA..theta. along L. The detector looks for targets 620 as
desired locations on the prosthesis to be coated. If the detector
finds a target, the applicator drop-on-demand 625. If the detector
does not find a target or after the applicator drop-on-demand 625,
the detector and applicator move .DELTA.x 630. The detector
determines whether it has traveled the full L of the prosthesis 635
by determining whether the sum of the .DELTA.x movements is greater
than or equal to L (.SIGMA..DELTA.x.gtoreq.L). If the detector has
not traveled the full L, then the detector and applicator move
.DELTA.x 640 and look for a target 620. If the detector has
traveled the full L, then the detector and applicator move
.DELTA..theta. 645. The detector determined whether it has traveled
around the entire contour of the prosthesis 650 by determining
whether the sum of the .DELTA..theta. movements is greater than or
equal to 360 degrees (.SIGMA..DELTA..theta..- gtoreq.360.degree.).
If the detector has not traveled 360 degrees, then the detector and
applicator move 615 linearly an incremental distance .DELTA.x and
.DELTA..theta. along L. If the detector has traveled 360 degrees,
then the coating is finished 655.
[0195] The present invention teaches a method for coating a
prosthesis as well as an apparatus for coating a prosthesis, a
system for coating a prosthesis, and an application control module
for coating a prosthesis.
[0196] It will be appreciated that the above descriptions are
intended only to serve as examples, and that many other embodiments
are possible within the spirit and the scope of the present
invention.
* * * * *
References